The invention relates generally to waste treatment processes and more specifically to waste treatment processes for non-hazardous, non-septic liquid waste streams.
Septic or municipal sludge waste streams are typically dried using thermal treatment processes that include mechanically pressing the liquid out of the sludge and further drying the solid using an indirect drying process or a direct drying process. The two step process can be unnecessarily costly.
For the second part of the process, an indirect drying process may include using drum dryers or rotary dryers to remove liquid from the sludge. Sludge treatment processes also use biological digesters to digest some of the sludge. The digesters anaerobically generate biogas, such as methane, that may be used to power the indirect rotary dryer. However, where waste streams are not septic, anaerobically generated biogas may not be available. Also, the additional cost of biological digesters to produce anaerobically generated biogas can become cost prohibitive in powering the dryer.
Direct drying processes typically use hot gas that is brought into contact and mixed with the sludge in a chamber to dry the sludge directly. However, such processes may generate odorous gases that need to be subsequently treated to remove particulate matter and to maintain an odorless treatment process. Also, such processes can be costly due to the power required to generate the heated drying gas.
Non-septic, non-hazardous waste streams processes typically do not use biological digesters due to the chemical makeup of the waste stream. As a general matter, waste treatment processes for hazardous liquid waste and septic waste differ from treatment process for non-hazardous liquid waste due to the nature of the waste streams.
Non-hazardous, non-septic liquid waste streams may include kitchen grease, run-off from car washes which include detergents, i.e., soapy, resinous, low solid feeds and high solid feeds. In addition, many landfill based waste treatment facilities do not traditionally process high volumes of non-hazardous, non-septic liquid waste since most liquid waste is sent to public owned treatment works (POTW) for treatment due to the cost in treating such waste streams. Generally, the cost of the energy source necessary to evaporate significant portions of the liquid from a liquid waste stream can be cost prohibitive.
Also, conventional methods for processing non-hazardous, non-septic waste streams or concentrated waste feed, such as waste streams incorporating filler, use mechanical presses to remove some of the liquid. The resultant effluent must typically be sent to POTW's for disposal thereby adding additional cost. The solid by-product is stored in landfills. However, the amount of liquid typically remaining in the solid by-product still causes the volume of the solid by-product to be excessive. This can cause unnecessary strain on landfill sites by causing the sites to be filled earlier than necessary. Also, waste feeds containing soapy content may foam excessively during such a process thereby requiring additional chemical treatment that may unnecessarily increase cost.
Typically higher solid feeds or higher concentrated waste feeds are more economical to process since less liquid removal is required. However, as the feed becomes more concentrated, processing can be more difficult since the concentrated waste feed may more easily clog feed lines, mechanical presses and other equipment.